Revivifying adsorbent materials



Aug. 13, 1929. r w, M STRATFORD I 1,724,531

REVIVIFYING ADSORBENT MATERIALS Filed Feb. 11, 1925 2 Sheets-Sheet I amoamtoz g- 1929- w. M. STRATFORD 1,724,531

REVIVIFYING ADSORBENT MATERIALS Filed Feb. 11. 1925 2 Sheefs-Sheet 2 uunnu nnuunn'unu zww wbiz @51 /4a wow/[y AW Patented Aug. 13, 1929.

UNITED STATES M. STRATFORD, OF PORT ARTHUR,- TEXAS, ASSIGNOR TO THE TEXAS COMPANY, OF NEW YORK, N. Y., A CORPORATION OF TEXAS.

REVIVIFZING ADSORBENT -MATERIALS.

Application filed February 11, 1925. Serial No. 8,334.

This invention relates to methods of treata type of decolorizing clay which has no ing fullers earth or clays or equivalent adnatural decolorizing power but which will, sorbentmaterial which has been used in de when treated with acid, develop an active colorizing. hydrocarbon oils and contemstructure so that the treated claymay prove 5 plates a process of removing adsorbed colorto be four to five times as efficient as ordiing matter and oil from the pores of the clay nary fullers earth. Certain clays of this and the restoration of the adsorbent and detype are so constituted that the degree of colorizing qualities of the clay. heat usually applied in recovery operations It is generally recognized that the colorwill practically destroy the structure of the 0 ing element in hydrocarbon oils consists of clay and render it worthless for decolorizing asphalt-like material in colloidal form and and refining hydrocarbon oils. when filtering these oils to improve the color The revivification of decolorizin'g clays thereof the colloidal asphalt is adsorbed on may be accomplished with much greater efiithe surface and in the pores of the filtering ciency by dissolving out the adsorbed color- 5 medium. For example, United States Leting matter by means of a solvent which has ters Patent No. 1,112,650 to Charles L. Parno harmful effect upon the structure of the sons, issued October 6, 1914, describes the clay itself. However, the power of dissolvadsorption and removal of impurities, ining such substances is not common to all eluding coloring matter, from oils by means types of solvents of asphaltic material but is of fullers earth. United States Letters Patspecific to a class of solvents which I Will e'nt No. 1,340,889 to Thomas T. Gray, issued designate as extracting solvents. Thus, for May 25, 1920, describes the deposition of an example, acetone is a fairly ellicient extractasphaltic or resinous deposit upon fullers ing solvent and by washing spent fullers earth used in refining oils in vapor form. In earth repeatedly with this material the as- 55 common practice the adsorptive clays generphalt-like coloring material may be substanally referred to as fullers earth which have tially removed and the clay so treated will been used in filtering petroleum oils are subbe revivified to approximately its initial effijected to a treatment in which the clay is ciency. On the other hand, should a light charged into a direct fired rotary kiln and fraction of petroleum such as naphtha be in contact with the gases of combustion. used to wash the clay, the quantity of color The coloring matter adsorbed from the oil ing matter extracted and the degree of revivand contained within the pores of the clay ification obtained will be negligible. Howis partially removed by a combined distillaever, on separating the acetone from the astion and oxidation but the decolorizing efliphaltic material which has been extracted,

* ciency of the clay thus treated is considerit may be shown that a large portion of this ably less than its original efficiency due to a extracted substance is soluble in naphtha. partial carbonization of the asphaltic mate- This example has been given to point out rial within the pores, thus reducing their the importance of what I have termed an size and also reducing the active surface of extracting solvent as distinguished from a 10 the filtering medium. Therefore, after sevnon-extracting solvent and to emphasize the eral recoveries, the clay has so deteriorated fact that all solvents of coloring matter or as to be of no further use in decolorizing oil. of asphalt will not extract such substances While the method of heating or burning from the pores of adsorbent materials. The which has just been described is used to a reason for such phenomena is not definitely large extent on the usual types of fullers known but a reasonable theory suggests that earth, such as that obtained in Florida and the asphalt-like materials dissolve in the exknown as Floridin, it is entirely unsatisfactracting solvents in the form of true solutory on certain other types of clays. For tions and are not readily adsorbed therefrom example, there has been recently developed while in the non-extracting solvents the apparent solution of the asphalticmatter is really a dispersion in colloidal form and in such colloidal solution adsorption takes place more readily. Whatever the true explanation may be, experiments have shown that certain solvents such as alcohols,ketones and like oxygen-containing carbon compounds are excellent extracting solvents to be used in revivifying spent fullers earth while other well-known solvents such as gasoline, benzol, and hydrocarbons in general, are not extracting solvents in this sense. I

It might seem then that thepreferable method of revivification of spent fullers earth would consist in treating the earth with an extracting solvent. However, the known extracting solvents belong to the more expensive class, and therefore, due to the unavoidable loss of solvent during treatment and handling of the clay, recovery by this method is so expensive that it has not to any great extent replaced the usual burning process except in special instances.

I have discovered that materials which are normally non-extracting solvents may, under the influence of heat, be made to function as extracting solventsi It may be that the temperatures most suitable for extraction will be above the normal boiling point of the solvent, in which case the solvent may be maintained in substantially liquid form by carrying on the process under suitable superatmospheric pressure. For example, I may treat spent fullers earth with petroleumnaphtha at temperatures up to its normal boiling point but the quantity of adsorbed coloring matter removed and the de gree of revivification obtained will be negligible from a practical standpoint. However, by the practice of my invention, I may treat the same or similar decolorizing clay with naphtha at temperatures in the neigh borhood of 600 F. and under pressures from 150-500 pounds per square inch or more, thus keeping the naphtha substantially in the liquid state, and extract therefrom a large portion of the adsorbed coloring material and effect revivification of the clay to a degree approaching its original efiiciency.

As a further example, the revivification of a spent decolorizing clay with an extracting solvent such as acetone may be greatly facilitated by carrying out the extraction at elevated temperatures and such pressure as is required to maintain the solvent in the liquid state. Whereas under'normal conditions the clay must be washed repeatedly with acetone to effect-revivification, if the process is carried out at relatively high temperatures the time of washing and extractmg is greatly shortened, resulting in a much more economical recovery'of the filtering material. y

The exact reason for this increase in exture of this solvent.

creased temperature may be to lessen the adsorbing effect or attraction between the molecules of coloring material and the surface of the clay. This latter eflect is probably of the most importance. Experiments have shown that'in decolorizing hydrocarbon oils, there is a temperature of maximum efficiency for each type of clay or adsorbent material. For example, ordinary fullers earth may be most eflicient at temperatures in the neighborhood of '100" F. whereas certain clays, both naturally occurring and artificially prepared, may exhibit their greatest decolorizing cificiency at 250-300 -F. and.

it is advantageous to carry out the revivification of clays by means of solvents at temperatures in excess of the temperature of the maximum decoloring clay.

In order that the invention may be more fully understood, reference may be had to the accompanying drawing, Figure 1, where theefl'ect of incrased temperature on the extracting qualities of different types of solvents is represented graphically. 'The curves are plotted with percent extracting efliciency as ordinates and temperature in degrees Fahrenheit as abscissa. A represents the extracting efficiency of a wellknown extracting solvent from ordinary room temperature up to the region of its critical temperature. The point of one hundred percent efiiciency taken at the approximate critical tempera- B represents the extracting efficiency of a usual type of non-extracting solvent. It is readily seen that at 80 F. the efficiency of the non-extracting solvent is negligible from a practical standpoint whereas the extracting solvent has at this temperature an efficiency of over eighty percent. The marked effect of temperatures upon the non-extracting solvent is shown by the fact that at 440 F A critical temperature of the extracting solvent, the non-extracting'solvent has increased in efficiency by approximately seventy-five percent, while in the region of its own critical temperature the non-extracting solvent of one hundred perefiiciency of the is arbitrarily the approximate oil upon which the clay has been used/will .130

effect to a considerable degree the efliciency of different solvents and therefore the curves as shown in the drawing are merely relative and are submitted only for the purpose of illustration.

In order to more fully disclose the application of my invention I will now describe in detail a preferred method of operation. Adsorbent material which has been used in decolorizing hydrocarbon oil, for example fullers earth, may be first treated to remove oil by washing with an oil solvent or by steaming or by a combination of treatment with oil solvent and steam. The clay is then charged into a vessel where it is treated with gasoline or benzol or the like while under the influence of heat. I may use any of the various well-known solvents of this type but I prefer to use gasoline or benzol because of their cheapness. I have found that in general the higher thetemperature used the more efiicient the revivification but this temperature is limited by several factors among which may be mentioned: 1. The critical temperature of the solventmust not be exceeded in order that it be maintained in substantially liquid form: 2. Cracking due to overheating, with consequent deposition of carbon upon the filtering medium is to be avoided.v

A preferred form of apparatus for practicing the invention is illustrated diagrammatically in the accompanying drawing, Figure II, wherein 1 is a strongly constructed and heavily insulated treating vessel in which the spent clay is placed,'resting upon the perforated plate 2 upon which is placed a wire cloth or similar material. Solvent is supplied from a source (not shown) by the pump 4 to the preheater 3 where it is heated to the temperature best suited for the practice of the invention. Pressure is maintained upon 1 and 3 so as to avoid excessive vaporization of the solvent. The solvent is passed through the bed of clay contained in 1 from which it dissolves and extracts the adsorbed coloring matter and any oil contained therein and is then expanded at reduced pressure through the valve 5 into the fractionating column 6 where vaporization and distillation take place. The heavy nonvolatile coloring matter and oil are withdrawn from the lower portion of the column at 10 while the purified solvent passes through the reflux condenser 7 and the condenser 8 and may then be returned to the preheater to be-used in further extraction. Circulation of the solvent is continued until no further extraction is accomplished after which the solvent may be drained from the clay and final traces removed by blowing with steam. The clay is then allowed to cool and is discharged through 10 to be again used in decolorizing operations.

While the invention has been described chiefly in connection with the revivification of spent clays, it is to be understood that it tions of the invention as hereinbefore set forth may be made without departing from.

the spirit and scope thereof, and therefore, only such limitations should -be imposed as are indicated in the appended claims.

I claim:

1. The process of eliminating adsorbed carbonaceous materials from adsorbent material spent in refining hydrocarbon oil which comprises forcing a heated solvent under pressure through a body of said adsorbent material.

2. The process of revivifying spent decolorizing clay which has been used in refining hydrocarbon oil, which comprises contacting the clay with a substantially nonaqueous solvent at temperatures above the normal boiling range of the solvent and under pressures in excess of the vapor pressure of the solvent at the temperature of contacting, and then separating the solvent and the revivified clay.

3. The process of revivifying spent decolorizing clay which has been used in refining hydrocarbon oil, which comprises contacting the clay with a substantially nonaqueous solvent under the influence of heat and under superatmospheric pressure, and

then separating the solvent and the revivified clay.

4. The process of revivifying adsorbent material which has been used in refining hydrocarbon oil, which comprises contacting the material with a volatile liquid hydrocarbon solvent under the influence of heat and pressure to effect the extraction of absorbed carbonaceous matter, and then separating the solvent and the adsorbent material.

5. In the process of revivifyingadsorbent material spent in refining hydrocarbon oil,

the step which comprises contacting the adsorbent material with a solvent, which under normal conditions of temperature and pressure has substantially no revivifying properties, at temperatures above the normal boiling range of the solvent and under sufficient pressure to maintain the solvent in a substantially liquid condition, to effect the extraction of absorbed carbonaceous matter. 6. The process of revivifying adsorbent material spent in refining hydrocarbon oil, which comprises extracting adsorbed carbonaceous material therefrom by forcing a heated solvent under pressure through a body of the adsorbent material, separating the solvent from the extracted material, and introducing the hot solvent into a vessel maintained under reduced pressure to effect distillation of the solvent.

7. In the process of revivifying adsorbent material spent in refining hydrocarbon oil,

the step which comprises contacting the adsorbent material with gasoline at temperatures above the normal boiling range of the gasoline and under sufficient pressure to 10 maintain it in substantially liquid condition to effect the extraction of the absorbed carbonaceous matter.

In witness whereof I have hereunto set my hand this 2nd day of February, 1925.-

WILLIAM M. STRATFORD. 

